gesetze-im-internet.de is operated by juris GmbH. They used to claim exclusive rights for their custom-made consolidated versions, and I believe they still claim something like that for historic versions available through their commercial subscription. (It so happens that juris also runs gesetze.berlin.de.) These juris versions are often viewed as authoritative, despite being made by a private company outside of the legislative process. There's another completely non-official website called buzer.de, which handles this so much better.

If you want to read the actual law as published, that's another commercial service (Bundesgesetzblatt, run by Bundesanzeiger Verlag), and there, the company claims protection rights as a database work. You are expected to buy a subscription if you want to print or search the PDF files they offer for viewing, or apparently for any kind of non-personal use. Unlike gesetze-im-internet.de and despite its commercial nature, Bundesgesetzblatt is an official federal publication.